为实现白天红外光电测量系统对低信噪比恒星的质心及能量高精度计算, 本文给出一种高效的方法。首先, 分析了红外光学系统白天恒星的成像特征。其次, 先对采集的图像序列进行预处理操作得到预处理图像。接着对预处理图像序列执行叠加求均值和下采样操作得到下采样图像。在下采样图像中以亮度为特征求取恒星的疑似位置后, 在预处理图像序列上建立与疑似位置相对应的目标区域, 在目标区域内顺序求取质心序列。对目标区域的图像序列以质心偏移为基础进行移位相加后获取目标图像。在目标图像上以信噪比为判据完成恒星提取, 以及质心和能量的计算。再次, 分析指出此方法能增强目标信噪比的原理, 并给出其适用范围以及相关参数的确定方法。最后通过实验表明, 采用移位相加法可增强目标的信噪比, 并提高提取正确率; 且对于SNR不大于48的恒星可将其质心和能量计算精度平均提高006 pixel和285%。移位相加法对低信噪比的恒星可较为精确地计算其质心和能量。

In order to accurately calculate star′s centroid and energy in infrared electro-optical measuring system in daytime for low SNR star, an efficient method is presented. Firstly, according to the optical characteristics of electro-optical measuring system, the imaging characteristics of stars during the day are analyzed. Secondly, in order to obtain pre-processing sequence, these operations, which include non-uniformity correction, bad point′s correction and background subtraction, are performed orderly in the acquired image sequence. Then a down-sampled image is got by performing image-stacking and down-sampling operation in the pre-processing sequence. Stellar suspected position is obtained by brightness characteristics in the down-sampled image, and a target area is located at stellar corresponding suspected position in the pre-processing sequence, then centroid sequence is extracted from the pre-processing sequence inside the target area. The sub images inside target area whose center is at the centroid are shifted and averaged to get a target sub image. Star extraction, centroid extraction and energy calculation are performed in the target image by stellar SNR criterion. Thirdly, the principle of this method to improve target SNR is revealed, its scope of application and the ways to determine the relevant parameters are analyzed. Experimental results indicate that the proposed shift-and-add method can improve target SNR and the extraction accuracy, for stars with SNR less than 48, its centroid extraction and energy calculation accuracy are increased by 006 pixel and 285% in average, respectively. Thus the shift-and-add method can achieve more accurate calculation of centroid and energy for low SNR star.